Is It Dangerous to Have a Crush While in a Relationship?
A new study investigated the consequences of having a crush on relationships.
Posted October 18, 2025 | Reviewed by Kaja Perina
Imagine the following situation:
Molly and Peter have been dating for five years and are in a committed and happy relationship. One day, Peter accidentally overhears Molly talking to a friend about having a massive crush on the tennis coach who trained with her during a recent resort vacation to Greece. Clearly, Molly is feeling romantic attraction towards the tennis coach, but it is also clear that she does not make any actual attempts at flying back to Greece to meet him again.
What Molly experiences is not uncommon:
It has been estimated that up to 70% of people in committed exclusive long-term relationships develop a crush on a third person at some point in their relationship.
Is such a crush a harmless experience, or does it pose a threat to the main relationship?
A new study, just published in the scientific journal Personal Relationships , now focused on finding out under which circumstances a crush on someone could have negative effects on the main relationship ( O'Sullivan and co-workers, 2025 ). In the study with the title “Do Crushes Pose a Problem for Exclusive Relationships? Trajectories of Attraction Intensity to Extradyadic Others and Links to Primary Relationship Commitment and Satisfaction”, the research team analyzed data from 172 volunteers who reported having a crush on someone else while being in a committed long-term relationship. The volunteers filled out various questionnaires about their background, about how strong the crush was on a person who was not their partner, and about the quality of the relationship with their partner. Each volunteer was tested at a baseline session and three more sessions, four, six, and twelve months later. This way, the scientists could investigate the time trajectories of how a crush affected their committed romantic relationship .
Crushes are mostly (but not always) harmless
Overall, the volunteers felt an average attraction towards their crushes around 4 points on a zero-to-eight scale. However, the sophisticated statistical analyses that the scientists conducted revealed that three distinct types of crush profiles varied regarding the intensity of the crush and the satisfaction with the committed relationship:
Taking these findings into account, what is the answer to the question in the title of this blog post?
Most likely, it is “It depends.”
The largest group of crushes seems to be harmless and has little effect on relationship satisfaction with the partner. Most likely, Peter had nothing to worry about when Molly had a little crush on the tennis instructor. However, the study shows that some crushes seriously affect the main relationship, especially if a strong crush exists for a longer period of time or the baseline relationship satisfaction is already low. Thus, a happy and loving relationship is unlikely to be affected by a little crush, but if things already look bleak, crushes can be dangerous.
Facebook image: ShotPrime Studio/Shutterstock
O'Sullivan, L.F., Belu, C.F., & Tramonte L. (2025). Do Crushes Pose a Problem for Exclusive Relationships? Trajectories of Attraction Intensity to Extradyadic Others and Links to Primary Relationship Commitment and Satisfaction. Personal Relationships , Volume 32, Issue 4, e70033.
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Sebastian Ocklenburg, Ph.D., is a professor for research methods in psychology at the Department of Psychology at MSH Medical School in Hamburg, Germany. His research focuses on left-handedness and brain asymmetries.
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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.